Aqueous Processing of Atmospheric Organic Particles in Cloud Water Collected via Aircraft Sampling

Environ Sci Technol. 2015 Jul 21;49(14):8523-30. doi: 10.1021/acs.est.5b01639. Epub 2015 Jun 26.

Abstract

Cloudwater and below-cloud atmospheric particle samples were collected onboard a research aircraft during the Southern Oxidant and Aerosol Study (SOAS) over a forested region of Alabama in June 2013. The organic molecular composition of the samples was studied to gain insights into the aqueous-phase processing of organic compounds within cloud droplets. High resolution mass spectrometry (HRMS) with nanospray desorption electrospray ionization (nano-DESI) and direct infusion electrospray ionization (ESI) were utilized to compare the organic composition of the particle and cloudwater samples, respectively. Isoprene and monoterpene-derived organosulfates and oligomers were identified in both the particles and cloudwater, showing the significant influence of biogenic volatile organic compound oxidation above the forested region. While the average O:C ratios of the organic compounds were similar between the atmospheric particle and cloudwater samples, the chemical composition of these samples was quite different. Specifically, hydrolysis of organosulfates and formation of nitrogen-containing compounds were observed for the cloudwater when compared to the atmospheric particle samples, demonstrating that cloud processing changes the composition of organic aerosol.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Aerosols / analysis*
  • Aerosols / chemistry
  • Aircraft
  • Alabama
  • Butadienes / chemistry
  • Environmental Monitoring / methods*
  • Hemiterpenes / chemistry
  • Hydrolysis
  • Mass Spectrometry / methods
  • Monoterpenes / chemistry
  • Nitrogen Compounds / analysis
  • Nitrogen Compounds / chemistry
  • Particulate Matter / analysis*
  • Particulate Matter / chemistry
  • Pentanes / chemistry
  • Spectrometry, Mass, Electrospray Ionization / methods
  • Sulfates / analysis
  • Sulfates / chemistry
  • Water / chemistry

Substances

  • Aerosols
  • Butadienes
  • Hemiterpenes
  • Monoterpenes
  • Nitrogen Compounds
  • Particulate Matter
  • Pentanes
  • Sulfates
  • Water
  • isoprene